POLYKRISTALLINE SINTERKOERPER AUF BASIS VON LANTHANHEXABORID UND VERFAHREN ZU IHRER HERSTELLUNG

摘要

The invention is a polycrystalline sintered body based on lanthanum hexaboride and having a density of at least 95% of the theoretical density. The sintered body comprises lanthanum hexaboride, boron carbide and amorphous carbon, the content of B4C+C being from 0.1 to 10% by weight and the total amount of La+B+C being at least 99.0% by weight, in each case calculated on the total weight. The sintered bodies have a homogeneous microstructure with mean grain sizes<10 mu m, in which, in addition to the crystalline lanthanum hexaboride phase, boron carbide and carbon are detectable as separate, finely divided phases. The sintered bodies can be manufactured by pressureless sintering at temperatures of from 2150 DEG to 2200 DEG C. from powder mixtures comprising lanthanum hexaboride and, in addition, mixtures of a carbon-containing material and a boron component.